This invention relates to a mechanism for incorporation in a photographic camera for handling self-developing photographic film and for processing it after exposure. The mechanism provides all the film-engaging structure for a camera of the self-developing type, but leaves other elements of the camera free for design independent of film-engaging requirements. The invention also provides a unitary transport receptacle for such a film-engaging mechanism.
The invention enables persons not skilled in the handling and processing of self-developing film to configure cameras in many varied ways and, by incorporating the mechanism of the invention, consistently to obtain high quality photographs.
The processing of self-developing film, to transform the latent image impressed thereon by exposure to a permanent visible image, is a complex process which requires the precise control of many parameters. Consider for example the processing of self-developing film of the type available from the Polaroid Corporation in Cambridge, Mass. for use in that company's cameras sold under the registered designation SX-70 and PRONTO! This film is in the form of separate card-like film units, each of which has a multi-layer construction with an opaque back and a photo-sensitive front and which carries along one margin a set of rupturable pods containing fluid photoprocessing composition. After exposure, the film unit is advanced through a slot in the film-storing cassette to transport it from the cassette to the nip between a pair of spread rollers. The spread rollers rupture the pods and spread the photoprocessing composition between layers of the film unit across the entire photosensitive surface.
Successful processing of each film unit in this manner depends on numerous factors, including the shape of each roller and the force between them, the physical constraints on the film unit as it exits the cassette slot and spans the space from there to the roller nip, the configuration of the film unit during engagement with the rollers and thereafter, and the masking of light from the film unit for a brief interval after passage through the rollers. These and related factors typically are carefully controlled, with structures that are dimensioned with tolerances measured in terms of ten-thousandths of an inch, i.e. 0.0001 inch.
The manufacture of self-developing cameras is more likely to become available to numerous firms provided each film producer is assured that cameras of others process the film correctly. This is necessary to ensure customer satisfaction with the film and thereby preserve the reputation of the film producer. However, it is likely to be excessively costly for each camera manufacturer to develop its own expertise to provide a film handling and processing mechanism that meets the exact requirements noted above.
Therefore, it is an object of this invention to provide a separable camera mechanism for providing the film-engaging operations for a self-developing camera, and which imposes minimal restraint on other functions and aspects of the camera.
Another object of the invention is to provide a mechanism of the above character suited for incorporation in cameras of varied design and configuration. It is also an object to provide a mechanism of the above type which is relatively low in manufacturing cost, and which is compact in size.
Thus it is an object of the invention to provide a mechanism for incorporation in cameras designed by others and which a film supplier can provide to assure that its self-developing film is handled and processed in the exacting manner required for reliable top quality performance.
It is also an object of the invention to provide a unitary transport receptacle for a film-engaging mechanism of the above type and which provides at least the film storage, positioning, and initial transport operations for a self-developing camera, and which configures and constrains the film for proper feed into the processing rollers.
Further objects of the invention are to provide a transport-receptacle of the above type which employs construction techniques and materials familiar to the camera industry, and suited for relatively efficient manufacture even in comparatively small volume.
Other objects of the invention will in part be obvious and will in part appear hereinafter.